How to treat company loan to connected company

Ltd company A owned by husband & wife (60:40 shares) and doing very well.

Husband decides to try a new venture (much to our horror as he had no experience in this field) and sets up Ltd company B with same shareholding.

Company A lends £40k to company B at commerical rate of interest (7%) to pay for stock and set up.

Problem arises in that company B makes a large loss in its first year and sells almost nothing. Husband is looking to cease trading and wind the company up.

How do we treat writing off the loan in company A's books?

Does the write off bring no CT relief in company A and would the write off be treated as a distribution to the 2 shareholders? If so, is there any way to avoid this?
 

Advice much appreciated.