the Mig29 is a nice aircraft and whilst it is a formiddable fighter in its own right, getting parts and more importantly getting parts that actually meet UK aviation standards would make it very costly to maintain. F16 again although cheeper to purchase initially, is costly to maintain.
Eurofighter however is more then capable of out performing the pair of them. Can carry heavier weapons loads then both and go further then the F16.
You are correct in saying that overwhelming numbers would eventually wipe out a technologically more advanced foe. However, as was shown in the falklands, where a 10 - 1 advantage against us was present, technology does count for some things. Argentines lost fighters in double figures, whilst we lost none in air to air combat (We lost two harriers due to AA fire).
A bit of inovation, well trained and well motivated pilots will even against statistically impossible odds.