Thank you guys.
CA are sending me out an employment form to fill in which should give them an idea of what I'm doing.
As for the Rob's advice about the pension, as I'm working in local government we're automatically opted into the pension scheme. Additonally, I'm hoping that I'm also entitled to the cycle-to-work scheme which would also lower my take home pay and also take me under £100 per week.
I lost thousands of pounds because I didn't realise how to make all the complicated earnings rules work to continue to claim carers allowance. If you are sufficiently determined and earn under £200 per week before tax and NI etc, (averaged out over several months where earnings are variable) it is almost always advantageous to force your residual earnings under the £100 threshold through the judicious use of legal allowances such as deducting care costs, work-related costs, and private pension plans - which anyone in work can join, whether they have an existing pension or not. (by the way, some government schemes allow for additional voluntary contributions, or AVCs) . Whilst only 50% of such deductions are permissible, the 20% tax you have already paid on PAYE is refunded into the pension pot afterwards, so it is worth taking the long view if you possibly can.
And of course, you can join a Union and deduct your subs as well - which I am sure you won't need prompting about, Alex - which apart from the employment protection aspect and solidarity is often a good investment with lots of useful benefits and discounts on mortgages and insurance.