Organising your finances in order to minimise tax, based on the allowances which are offered by HMRC themselves is NOT tax avoidance or morally corrupt or any of the other drivel spouted here.
Does anyone really want to pay more tax than they have to because of some supposed moral obligation??? Even the Money Advice Service, funded by the FCA, a regulatory body, gives advice on how to reduce tax. I'm amazed so many see this as some awful immoral thing to do, and yet a poster can ask "will I get tax credits / benefits if I......?" It seems there is no shame in being entitled to take out of the system but an utter shame in being entitled not to put so much in.
OP. The first thing to do would be to check whether you have any salary sacrifice options open to you through your employer. Pension schemes, childcare vouchers, car and parking, work related training are often offered and if you take them up, it can reduce the amount of your taxable salary.
You can claim tax back on a whole bunch of work related things, fuel, clothing, expenses. It's worth having a look at HMRC and seeing if any of them apply.
You could also look at doing your own tax return. This way you can use all the offsets above but also gain advantage from things like interest on savings, charitable giving etc.
It might be worth looking at a financial adviser, but it may also be that the cost of that could outweigh any savings. Have a look and see what you can find on teh HMRC website first.