Assuming your employer or supplier or customer aren’t reimbursing your costs….
If you’ve got to make journeys for business purposes you can deduct your traveling expenses from your taxable income – so you’ll pay less tax. (If they pay and its ‘wholly and exclusively’ for business they get the tax deduction and its not a benefit in kind)
In addition, there is no restriction on the standard of travel and accommodation, provided the main purpose of the trip is that of business, you can travel first class and stay at the best hotels.
But what if the trip is partly business and partly pleasure, in this case you will need to apportion the costs and only claim for the business element.
The problem comes if the hotel bills somethings outside of the normal package for example a round of golf, this could well become a taxable benefit.