Assuming a unit cost of £0.25 GBP (which is about the best rate currently available in UK), if you bought the most efficient BTC miner currently available (S21 XP, 270T) you should expect to lose approximately £10.00 GBP per miner, per day.

You need access to cheap electricity (e.g. generate it yourself) in order to make profit from BTC miners.

It might be worth considering some Antminer L9 (Scrypt), these would currently make around £16 profit per unit, daily - but will have a much higher outlay. £50k would buy you about 5 units.