Good evening, thank you for your messages. I am not aware of the Consumer Credit Act 2013, however it is not easy to fully understand the circumstances of a case where you give very minimal detail.
What counterclaim do you have? What you have descxribed to me is a Defence and I do not see what damages you have suffered in order to also file a counterclaim.
Assuming that you have got it right that you entered into an off-premises contract and that you are saying in any communications that you had no mention was made of the cost/price of the works for which you were speaking with the trader ( it is possible but you must be conscious that a price communicated to you even though it is not in the contract document would satisfy Schedule 2(n) as long as you knew the price from the contractor but if no mention at all was made then my guidance below applies to your situation)
What you ought to correctly make reference to and rely to is The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 and your Regulation to quote is Regulation 6 which states :
(6) The consumer bears no cost for supply of the service, in full or in part, in the cancellation period, if—
(a)the trader has failed to provide the consumer with the information on the right to cancel required by paragraph (l) of Schedule 2, or the information on payment of that cost required by paragraph (n) of that Schedule, in accordance with Part 2, or
(b)the service is not supplied in response to a request in accordance with paragraph (1).