Hi Robin Right dependant on how keen you are to clean your car depends how much you are prepared to spend. This is what I call the starter kit circa £115.00 . Once I know it has loaded I will put a write up under the photographs/I bought the larger quantities 20Ltr not available on line. it’s up to you Red Thunder or Outrageous Orange. “READ INSTRUCTIONS” on all the products.
So you will need 4 spray’s 3 for the cleaning products 1 for clean water, WD 40 comes with spray gun.

This is the one I have used ever since it was available in UK £19.94

Some think this is better than Red Thunder but it was not around when I started £19.94

This product id un believable £23.79

Although expensive it’s brilliant £23.00

Normal Garden centre price £26.29 each Amazon £13.35 each looked after will last years.You need 4 I found an offer box of three +1

Much cheaper than the spray cans £22.25 5 Ltr’s + applicator
Not sure if this will work if not can you delete it please Laurence.
Worked great as EDIT working OK today,