Welcome from me & the tribe too!!!
Yep!!! I agree, neuter asap before an 'accident' happens!!! Tomcats are very persistant and will try to get at her anyway they can... including coming in through windows etc.... also she will want her 'need' attended to and will often try escape attempts to find the tomcat of her dreams!!!
If you and you family & friends still want to home another cat, PLEASE, please go to a rescue centre... All mine are rescued and (until this morning, see crisis in bahaviour section) they have bonded really well!
I'm not sure what London area you are in but msg me & let me know, also give details on your living situation, homelife & her personality, as I work for a Norfolk rescue & we have contacts throughout the UK and I maybe able to suggest an appropriate match?!! i'm pretty good with matching personalites of cats and owners.... have had 6 successful matches with people I work with so.....