Yorkshire Autodrome is OK and cheap but a bit boring and narrow. For the Yorkshire lads consider Oulton Park a great circuit and only an hour and a half away. Cadwell is also a great option and Blyton which is a tad closer than Cadwell but not as exciting.
Sherbourne and Blyton are great beginers tracks or testing tracks for new set ups etc but nothing beats a real circuit.
Finally, Croft in North Yorkshire is a good circuit too and not that far away.
All that said, £40 is nothing for a days fun and I fancy tagging along