Being in the IT consultancy trade, I have read and heard a lot about talking to the Inland Revenue recently.
I would recommend NOT talking to them - it's akin to laying all your cards on the table. And whatever one of them might say or agree, another one can still investigate you and come up with their own judgements later.
They are a particularly dogged and obtuse bunch (take it from me, I've even worked for them for a while!) and none that I know of understand the ins and outs of aircraft operation. They also (generic view I know, and bigoted but there you go...) seem to envious of any self-employed person's success. Profit & growth seem to equate with dishonesty to them. This extends to the politicians who supposedly control them, who have placed some amazingly illogical and unworkable taxation policies in the last few years (known in the trade as "IR35").
You may be totally in the right legally and company operation-wise, but may still incur vast expense defending your position against their attentions. Best not to attract their attention in the first place (and I don't mean by doing anything illegal - I mean by trading totally straight and down the line, in accordance with UK legislation and accountant's help and advice),
The best I can suggest is that you (a) indeed talk to your accountant (maybe find one first that understands GA operations)and (b) hold as much supporting paperwork for both business and private use as you can, and if you want to be really pedantic but well covered, keep a diary of what you did and what the weather was every day.
I keep invoices for personal aircraft hire, but when I first bought the aircraft, I did about 10 hours ferrying around to get bits done on it for the public cat. I'm claiming those as legit flying expenses. But when I used it for a w/e trip to Wales with my wife, I invoiced myself and paid a hire amount to the company.
Believe me, the IR have tried to get people for the sheer availability of their aircraft over a tax year (eg "your areroplane was there for 365 days a year, with xxx hours of daylight, therefore you had potential use of it for xxxxx hrs, therefore, you owe us £yyy at an hourly benefit rate of £nn").
What really pXsses me off is the hordes of people who live in the black economy, claim benefits and grants but are never pursued by the IR or Govt because it's seen as politically incorrect to do so. My wife went on an IT training course last year - we paid £600 for it because I was earning so she wasn't eligible for a grant. No-one else in the class had to pay - they were all on benefits, and from what was said (by them), the majority were only doing the course so they could get their kids minded at nurseries and continue to claim benefit. Most of them were dripping with jewellery and had boyfriends who (of course) didnt live with them but seemed to be very cash rich.
But there - I'm just a old bigot and should be shot at dawn for daring to question the way this country runs. Rant mode off...