In terms of money I would suggest the car test.
Although you have to do the theory test again whichever you opt for in the case of the motorcycle you have to do the CBT again.
So the motorcycle test is Theory, CBT. Module1 Test, Module 2 test. Off set perhaps by the fact you only did the bike test a year ago and are perhaps more familiar with the requirements.
The car is Theory and practical. Done. Might need a bit more boning up as it was some time ago.
You are probably familiar with it but - http://www.direct.gov.uk/en/Motoring/Dri… - is the link for DVLA's info on extended tests.
They cost about the same but I reckon you will have more chance of passing in a car
I feel sure the car test is cheaper so go for that.
Hi glad your getting through this, one thing you might want to consider is sign up with the IAM, Institute of Advanced Motorists/motorcyclists too. They do do bike training usually with the local police force motor cyclists, who do teach you what you need to know and a few 'other' bits as well!
I did my test many years ago so things may have changed slightly, alternatively look through MCN or contact any of the UK motorcycle race tracks and ask about track days. These albeit a bit pricey now are well worth the spend as your in a traffic free race track.