Hi sorry to hear why you're here,
We buy any bike do so at prices even less than dealers offer as a part exchange price IMO, but will give you a worst possible price which you can then use when using the options below:
Most pounds to you option, take some pictures and post an advert on here.
Or on Ebay. Completed sales can give you an idea of what other similar bikes have been sold for.
Or, get a dealer to have a look at it and give you an offer.
Fastest is probably the one that will be the least money to you, but that might be better for you. Hope it goes well whatever you choose.