Why not just sit the test? it's not hard and if you plan to tow then you should be able to do so before you hit the road. The cost of a new car, tax and insurance will surely be more than the test ( mine was £160 including lessons ) and adding you to your OH's car insurance.
You can then tow with a suitible car and not risk the lives of yourselves or others by using a car that is on it max limit. sorry to be a pain but it gets on my wick when people tow without experiance or the right type of car for the job.
Do you have any idea how i can find where there's instructors in my area? Or do you not need an instructor lol!