Hi Evesmum
There will be some claimants who will loose out when they are to apply for UC.
Once you receive the invitation to migrate letter you have 3 months in which to apply, in the meantime your WTC will stay in payment.
I would advise you to seek help from your local Welfare Rights Organisation as you need to seek specialist advice;
advicelocal.uk If you do not qualify for UC then you do not have to put yourself through the stress, but seek advice before you do anything, one way or the other.
Gary