If it's bits you NEED to take, like for the laws then yes.
Each country is slightly different in some laws but to be safe you need.
A warning triangle.
A spare set of bulbs.
A GB sticker, either on the car or on your number plates.
A first aid kit, preferably new or sealed.
An hi vis jacket for each person in the car
The other thing is a fire extinguiser but i don't think this is needed but recomended.
Lastly you need a way of converting the beam on your lights, i have a set of Alfa headlight protectors with tape permaently on so you can copy the position of this with some black insulation tape.
Most insurance policies allow for 90 days cover in europe at no extra cost and a phone call before you set off is all that is needed, when they ask were you are going, tell them, France, Belgium and germany. thats enough.
A passport, valid one at that, check now when ity runs out, not last off.
You should also take with you your car documents, Log book, MOT certificate and insurance and of course your licence, both parts. you are european (i'd imagine) but these will only be needed to get out of and back into this country.
For piece of mind you should take out european breakdown cover, if you are in the AA/RAC this can be had for about £50 for a 5/6 day trip, again this can be purchased before you go, months in advance if you like so it is not something you have to shell out for the same week as you are out there, again saving.
Don't get me wrong, it'll probably cost you a good £5/600 for a week out there but if your a petrolhead it'll be money well spent, you'll be out there with like minded enthusiasts all looking to have a good laugh and a good time.
Prostitution is legal there too