Not too sure if you need to remove dash but ours was changed a couple of years ago and I'm sure the dash stayed in.
Before you change the eps check the connection on the silver box in the passenger footwell. This can get knocked by passenger feet it's in the middle of footwell under front of carpet on bulkhead.
When our eps was changed it still didn't work, I rang the supplier and he asked if I had check this connection, I then did and 'Bingo'. So the old eps was OK, the connector had been knocked when we had a new clutch cable fitted! So £320 (parts & labour)spent for nothing!!!