I've managed to source Yoki 195/50R15 for £62.30+ each, now I believe this to be a good price is there any others I brands I should consider before shelling out?
depends if you want to go road legal or not. toyo r888, or there are some others by hankook, kumho, avon, and some premium brands. some road legal some not.
maxsport/indy sport, type of intermediate tarmac rally tyre are also worth a look. http://www.ears.co.uk/p299/195/50-15-Indy-Sport-TR5-Tarmac-Rally-Retread-Tyre/product_info.html
i've got r888s on my race golf and they have been fine on the road and on the track sessions i've done. slicks and intermediates can be had second hand for decent money if you look about or find a race teams that use your size.
not come across those tyres yet. check the reviews online to see what gets said about them.
shand can be cheap way of getting good track tyres. the scottish mini championship use 195/50/15 a048 as control tyres, if you know folk in it then you an pick up cheap tyres. it's a pain but changing wheels at the circuit can open up more opportunities, a lot of trackday tyres can still be good beyond legal road limits. so use legal wheels to get there then chuck on the race wheels once there. most circuits have a garage or 2 open for storage of stuff as they realise folk bring spare wheels. etc. just make sure you torque them right before going out!
just watch for the measurements on motorsport tyres. sidewall and width can be different mm/cm/inches which needs some investigation to work out "what's, what" and close to what you want.