I've raised £700 to Pay for the removal of a lump on Baileys Spine

Bailey needs to have an operation to remove a fatty lump from his back near his spine, unfortunately his insurance won‘t cover it and the estimate has come in at £622.64 and another further £80-£100 to have the lump tested to rule out malignant cancer.
Bailey was my dog from 6 weeks old, but due to a marriage break down I had to leave him in the care of my soon-to-be Ex Husband almost 3 years ago. I received a call 4 months ago to say Bailey had been dumped in someones back garden 6 months previous and I rushed down to immediately take him back into my care. He was very poorly and the lump was already on his spine, because of this the insurance classes it as a pre-exisiting condition and will not cover the removal. We have had many vet visits since I got my Bailey back and he is now in good health again ready for his operation. I desperately need help to raise this money so I can get my Bailey back into a full bill of fitness before it grows any bigger.