If you are going to an Indy, and have a reasonable idea what you want, make a list and ask them to quote you.
For instance, if you want oil and filter, get them to quote for time and parts, also you NEED to know what parts they are using, the spec and make, otherwise you may well get a chinese filter and chip pan oil
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It is worth investigating doing some things yourself. why not consider changing oil yourself, and filter, and air filter.
Gap some new plugs if needed and pop them in. buy a decent manual if you are unsure. Check the suspension etc where possible yourself, all lights and fluids and tyres etc can be checked at home - no need to pay someone a fortune to do that !.
But, things that get complex or more involved, like changing brake fluid and clutch fluid, get them to quote, get the spec for the fluid and make sure they use it !! - get them to pay for the fluid as you will almost always use far more than expected when flushing / changing and you only need one seized bleed nipple to cause a total nightmare.
Look in your handbook and work out the simple things you can do at home. Then rather than book a 'set service'
instruct the garage to do just what you want them to with a full quote, in writing, in advance, stating type and make etc of parts/
Always ask for old parts back where practical.