Euro car parts have a sale on batteries at the moment, I got a 075 for £38. However while it does fit in the battery tray it doesnt exactly fit in the indent in the tray as it's too long, can be clamped down though.
Also borrowed a battery conditioner from a mate and that appears to have completely revived and tested ok the old battery, might be worth a try first if you know someone that can lend you one?