I am new to all this, I bought the property in 2018 but work on it took time.
I had to rewire the whole place to make it safe and meet renting standards.
Due to Covid was not able to rent till Dec 2020
I am filling in my tax return, I had a huge bill of £5000 for electrical work can I claim it as expenses but was completed in Oct 2019. Had no income so did not fill in any self assessment for 2019-2020.
As long as you bought the property with the intent to let it, you can claim any expenses that would have been allowable had the property been let.
So, you should be able to claim any revenue costs to date, including things like utilities, council tax etc
If the electrical work was needed when bought though, for the property to be fit to let, HMRC would probably argue it is capital (added to the cost for capital gains) rather than revenue (tax deductible from rental income).