You seem to be working your way through the options...
Visitor visas can be used for visits, but very likely to be denied if you attempt to use them to spend more than 50% of the time in the UK without good reason (developing a relationship is not a good reason...) as it appears that you are trying to settle in the UK.
Work visas might be an option, but it depends on skills/qualifications. And as andypaul pointed out it might look dubious if someone was offered a job whilst here on a visitor visa.
Student visas might be another option.. If you've got lots of cash you could try getting a 3 year student visa for a degree course. If you have less cash you could try getting a 1 year student visa for a part-time course - this would also allow part-time work.