Appreciate your help and concern. I am aware that the problem could be more than just the part that I intend to replace, so I`m going into this with my eyes wide open and my fingers and toes fully crossed.
I understand the potential dangers of messing around with air conditioning but am still going to do this one job myself.
At the very worse, I have wasted a saturday, as long as I don`t asphyxiate myself as I would have wanted to replace the condenser anyway. I`m confident that all the parts work as it worked when it was filled up, only for the gas to escape from somewhere. I hope to do the work today, I will take photos along the way if anyone is interested, I will post if someone can explain to me how.

I agree with the above - leave it to someone who has that magic touch. Many seals need to be tightened to "just right", which anyone experienced just knows the feel of. If I did it it would either be too slack or overtightened and buckled/stripped.

Despite Andy's head-banging, I still believe a knackered condenser should be replaced. As the system's already empty and it's crumbling it would be irresponsible not to, for the amount involved in buying one.

The pipes are made of the same material as the fins. If they're not already leaking they soon will be. This poor thing is exposed to every pebble that gets through the grille, plus driving rain and salt spray. Its second purpose is sacrificial, to protect the radiator from all this.

Personally, as a keen tightwad DIYer, my approach was that I took the bumper off myself, then a local independent mobile air con bloke fitted the condenser (that I'd bought from ebay) and refilled it, all in my driveway. He only charged a bit more than the refill alone - most of the cost is driving to your house and setting up.

Get the condenser fitted then vacuum tested. If this finds a leak then fine. If not then refill it including dye, but if it has a one-way leak as mine did (in the condenser in my case) then the first fill is sacrificial.

Knowing what I now know, I wouldn't have wasted money on the first fill, as a new condenser is less than a fill. If it's got no fins but doesn't leak then it still won't work properly anyway, and won't be far off leaking.

After the air con feller's refilled it you then have the task of refitting the bumper, which can be more challenging than it should be but is perfectly DIYable (well I did it anyway).

Well, I`ve taken off the condenser, without the need for removing the bumper completely. I managed to do it by only taking the grille off which is going to save me a considerable amount of time. I dont think that it will be necessary to remove the bumper to fit the new condenser either.
I think that I may have found a/the source of a/the leak. There are two connections on the condenser, one at the top and one at the bottom. On the bottom one, it looks very much like some liquid has leaked out and onto the threaded rod below, corroding it somewhat. Hopefully I can reseal this properly.
I have spoken to a local guy who will service, die check for leaks, vacuum, and regas so if there are any other problems, he will find and remedy.
So I hope that evrything will be running smoothly by this time next week.

Sounds good. I did look at the grille - there was a reason why I took the bumper off, can't remember why now. Perhaps I thought it would be easier until I found the rusty screws.

Good luck - let us know when it's all fixed and you're ready for the raging hot british summer.

Cheers Doofer, judging by your location, you will probably see more of the good weather than us. Here in Manchester, yes you`ve guessed, it`s raining !!
The wifes gone out for a few hours and I`m babysitting so I can`t get back onto the car, but I`ll be doing it later.

Fingers cross it does the job.

Well, I`ve changed the condenser, managed to dodge the rain and get it done over the weekend which I am extremely pleased about.
Couple of pointers to those wishing to do it themselves:

No need to remove the bumper entirely, just the grille will do.

If the replacement part is as the one listed above, it comes without the connection nuts. On the original, you can remove these, but they are not compatible.
The original condenser is "countersunk" where the nuts screw into the body, which is necessary as the body is wider at a certain point. However the replacement part is not and the wider part sits on the body so the bolt cannot be tightened flush with the condenser, leaving approx 1mm gap. I suspect this will cause a leak. Luckily I had some screwed rod (8mm I think) which I chopped a couple of short lengths off and used these.

Chap`ll be here any minute. Fingers crossed it all goes well.
I`ll let you all know asap.

Well guys, it`s all done !!

Thanks for all your help, I`m really pleased that is the end of that and the car is sorted. The trip to the south of France this August will be much better !!

The chap who did it was excellent, pressure tested everything, vacuumed and then re gassed the system, checking all the vents and temperatures. Wouldn`t hesitate to recommend to anyone else.

Yay! Glad to be of help - I get plenty help from others on here with my numerous issues, so glad to be of some use.

And another wad of cash doesn't go to a Fiat dealer!

could anyone give me an idea as to where the connector is located for regassing?
have the kit, but dont know where to attach it... bit thick there!!