I agree with the others, but that does not help. First, the legal bit:
- If you gave the other person the same level of detail in an Agreement similar to the one you have with your own landlord, and got her to sign it, then this is wholly your responsibility to sort out as you are her landlord.
- If your landlord did not know you sublet, and or the landlord did not agree to it in writing, then you are in breach of your Agreement with your landlord. The landlord can be nice and turn a blind eye to it, or ask you to leave because of it, but that is unlikely reading between the lines.
- In both the above cases, you as her landlord, and your landlord regarding your position as their tenant, are legally bound not to evict the tenant for at least three months, and in practice these two landlords (you and yours) may not get rid of their tenants for six months or more if the tenants (your and her) refuse to move.
Assuming she does have a signed agreement with you:
A) Tell her, each time in writing, that she has a legal obligation to pay and must do so by a specified date, or she will be evicted, and like G) below, give her three chances to comply then issue a Sect 8 notice of eviction, using the government website for the latest forms to use, and advice from your landlord, see https://blog.openrent.co.uk/how-to-serve-a-section-21-and-section-8-notice-of-eviction-to-tenants/
Assuming you do have a signed agreement with your landlord:
B) Check to see if you can sublet, and if you have to notify your landlord or not that you have done so, to give you peace of mind on breaking your agreement with your own landlord.
C) Ask your landlord if they will accept a reduced monthly payment from you for the time being until such time as your own tenant has been replaced by a paying tenant. You may have to pay the difference later when you can afford to do so. Have this in writing, e.g. email or letter. Also ask if your landlord will look for another tenant to replace your tenant as soon as she has left. You can do the same, but this time not sublet!
D) Of course you can look for alternative accommodation for her and you, provided you have less than two months of your fixed term left. You two need not live together. However, you will remain responsible for her unless your landlord agrees to take over your ‘landlord responsibilities’, even if you leave your current accommodation!
Assuming she has no signed agreement with you:
E) You could call the council for advice and to report her as homeless, as you have told her to leave for failing to share your costs. If they accept your position then it may take several weeks, perhaps two months, before they can find her alternative accommodation. My Council will only do this if children are involved, but there is no harm in contacting your Council.
F) Other than seeking legal advice, is to ask the police if they can remove her as she is trespassing, having failed to leave when instructed.
G) This is not nice, and may be too uncomfortable to do, with attendant risks of personal repercussions. At least you could go through the steps without acting out the final step, and that may be sufficient to get her to leave. Only do this if you have no written signed agreement with her: you can ask her to leave, or force it on her. I suggest you give her at least two written warnings to be nice, requesting she find alternative accommodation by a given date, unless rent is paid Give each warning about two weeks apart, then a final warning with a deadline. On deadline day, change the locks, give your landlord a spare key in case of emergency, and keep the old locks to replace the new ones when you eventually leave. On that deadline day, neatly pack her stuff and leave it in a safe dry place, or pack it sooner so that she gets the message before the deadline day. If left inside on the deadline day, you may have to let her in and tell her to leave, and possibly call the police to report a trespasser if things get heated, or at least the next time she leaves put her stuff outside. If left outside on the deadline day, leave a note that she has to find alternative accommodation and the phone number for the local Council to ask for help. She can have the Council and a Shelter telephone number in each warning.