To do the tests properly you are looking at up to £500 worth of equipment!
An all in one tester from Fluke or Megger will cost that, see Megger 1502/2 or Fluke 1653 for two good examples, you could buy seperate instruments, but the cost will probably be higher still.
To do checks as you go you will need a low resistance ohmmeter (thats your multimeter), an approved voltage indicator (there are regs for this GS38) to prove live or dead, plus if you want to be thorough, an insulation resistance checker (what most people call a 'megger' (trade name)) and an earth fault loop impedance checker. then you have to test the tripping time of your rcd (mS) I think that should suffice, probably easier to let labc send round a registered spark imo (he's already spent the money on all that kit and this is partly what you pay for when using a reputable tradesman).
If you follow the regs (BS7671) and stick to approved accessories then you wont go far wrong and can leave the testing to labc, by the way to do all this you must be 'competent' (ask about competency and you'll open up a huge can of worms
)
Top tip: use a registered spark.