They'd need a good excuse because you don't fall under the distance selling regs.

Gilbertd wrote:

They'd need a good excuse because you don't fall under the distance selling regs.

Thanks for that. What about 'cool-off period' ?

From https://www.citizensadvice.org.uk/consumer/changed-your-mind/cancelling-a-service-youve-arranged/

"If you paid up front or made a deposit and cancel in the cooling-off period you’ll be entitled to receive all of the money back. The only exception is if you asked for services to be provided during the cooling-off period, in which case the business will keep what’s necessary to cover the cost of services provided up until you cancelled."

I would imagine that the labour (of fitting the lpg system) would count as services provided? Might be different in the event you were selling bits to be fitted rather than selling bits and fitting them.

This bit from the same page also relevent

Cancelling a service you arranged while on the business’s premises
If you haven’t formed a contract with the business for the services you won’t have to pay anything. If you’ve paid up front for the service or made a deposit you’re entitled to get all of it back.

You may have a contract even if there’s nothing in writing, for example if you’ve accepted a quote, paid the fee or a deposit or verbally told them to go ahead with the service.

If you’ve formed a contract with the business and you cancel, you’re unlikely to get all your money back unless there’s a generous cancellation clause written into your contract.

The business could:
charge a cancellation fee
hold some or all of your deposit to compensate for their financial loss (eg where they set aside time to provide the service and can’t book another job for the same period)
demand money if their loss due to your cancellation isn’t covered by any deposit

That's what I would have presumed thanks Bri.