Thank you for the kind words. Here is a good link on vat thresholds
https://www.gov.uk/vat-registration/when-to-register
The important bit is to remember that HMRC are a humourless bunch who love to enforce the rules to the T. So, the threshold for now is £82,000 in any 12 month period, or you expect to go over that in any 30 day period. So put another way if you turnover, that's invoice values exceed £82,000 in any 12 months past present or forecasted you must register for vat and charge 20% on parts and labour. In real terms that's only £6,900 worth of invoices per month, or £1500 per week. The benefit is that you get to claim back vat on certain items, the biggest downside is you immediately price yourself into a different league of tradesman. One small trick to keep turnover down is to get the customer to supply bulk materials. Several benefits to this: materials do not appear on your turnover, you are not liable for any warranty or guarantee under the sale of goods act, you are not left out of pocket if the customer decides not to pay leaving you with little chance of getting either the goods or the money. Of course you won't be able to up charge materials supplied, but in my view that's a small negative compared to being vat registered. Unless, of course, you are going for it and trying to grow the business and become an employer with premises etc.
So it's worth keeping your books up to date with a simple system so that at any one point in time you can say with certainty: this is my running turnover, this is my current gross and net profit. Sounds daunting but it really is not once you have simple spread sheets set up on excell. In fact I would go as far as to say that after a few months you will soon feel very much more in charge of your business as the unknown is removed.
Turnover is defined by HMRC as
VAT taxable turnover is the total value of everything you sell that isn’t exempt from VAT.
You must register for VAT with HM Revenue and Customs (HMRC) if it goes over the current registration threshold in a rolling 12-month period. This isn’t a fixed period like the tax year or the calendar year - it could be any period, eg the start of June to the end of May.
For a more exact definition of this see
https://www.gov.uk/vat-registration/calculate-turnover