1. Do you have any joint debts - such as a joint mortgage or current account? If you do then your credit records will be associated. If you don't, then they shouldn't be as you are not married.
2. Whether the mortgage is joint or not, the bankruptcy Official Receiver will want to identify your partner's share of the equity. If you can show that you have made all the payments & that your partner has only lived there a short time then the likelihood is that her share of the equity will be considered to be very low or nil. (I've known of a case where a partner was living with the houseowner & making some payments to household bills & the mortgage, but was deemed not to have any equity interest because the payments were considered to be no different fom what would have had to be paid if living alone in rented accommodation.)
3. She should do an income & expenditure statement for them, & offer �1 per month if she can't afford more. A lot of these outfits use threats without any intention of carrying them out. It would cost them more than �1000 to make her bankrupt & they are not likely to spend that if they realise it is most unlikely to get repaid.