Having a decent van is the number one requirement for WFP cleaning IMO and the largest outlay is your van. If you don't want to spend a huge chunk all at once then leasing for a small rental amount every month that's 100% tax deductable is ok. Its easily affordable for most businesses.
I just see it as a legitimate business expense every month now.
I was telling you this for years Daz when you were driving old bangers. “No need for a new van, sod paying for a lease, I only do 50 miles a week yada yada”, you said this for years, until you finally got a new van and it was suddenly the best thing you ever did. 
I prefer to buy a low mileage year old van, let someone else take the hit on the depreciation but still have all the benefits of the new van.
I'm allowed to change my mind.....
I spent a few years with old vans when I switched to wfp but then realised that I had to swap systems over every couple of years (when they finally gave up the ghost)which is a real pain.
I also wanted a diesel heater after faffing about with cheap(and dangerous!) gas shower units so it's not worth installing one in anything other than a brand new van IMO.
I ve got my dream van and system and I still love it 9 years on. I will get the timing belt and water pump changed next year.