I presume that its wheelie bin cleaning you are talking about from your name, your location doesn't matter a jot if you are in the UK.
The company you sub-contract to do the work will need their own insurances, and I'd guess you'd charge VAT on your invoice and would be liable for that part, the VAT they charge would be their liability. If neither company is VAT registered then no problem.
I could be wrong but this answer makes the most sense to me