@Marie7308 IF you definitely qualify as a Furnished Holiday Let then you will have an easy time for tax.
1) As FHL joint owners you can nominate what percentage of the profit goes to which person so a low earner can take 100% of the profit. Not sure what you mean by 'everything is in my husbands name'. If you are not on the property deeds at all then I don't know what the rules are.
2) I don't know what relevance you place in your profit being over 7500. I think this is a red herring
3) You should contact your council re business rates. Unless the house has lots of beds it is likely that you will pay ZERO under business rates and you might find the council refunds your council tax
4) You can elect to cash account the business which is much simpler than the other method so even an amateur can get the tax return right
5) FHL income can be used to fund a pension so you could, if you can afford the cash hit, start (or add to) a pension thus reducing your taxable income towards the 12570 yearly limit.
6) Being a FHL will mean paying Capital Gains Tax when you come to sell it.
All the above is my best understanding and I take no responsibility if it is wrong!!!!!