Coinbase Alternative for Sterling to Bitcoin

It would appear that they charge the following to change sterling into bitcoin
for £10 99p
for £50 £1.99
for £100 £3.84
And the max limit is £300/ day. And guess what they change for £300 £11.51!!!!!!!
Plus the system only works on a mobile phones and not on my computer so all in all very bad company to use
Anyone any alternatives please?