Talking Checklist,
In the United Kingdom you cannot claim a deduction for an expense that simply puts you in a position to undertake an employment. However you may be allowed a deduction for an expense that is wholly exclusively and necessarily in connection with your employment.
The relevant law is Section 188 (1) of the Income & Corporation Taxes act of 1988.
The 3 tests that need to be satisfied for an employment expense to be allowable are :
The holder of the office or employment must be "necessarily obliged" to incur the expenditure; and
The expenditure must be incurred "wholly, exclusively and necessarily" for the purposes of the office or employment; and
The expenditure must be incurred "in the course of the performance" of the duties of the office or employment.
So if you need a type rating in order to be employed by a company then it would ordinarily not be allowable. If on the other hand you were already employed by the operator in the capacity that required such a type rating and it was a necessary requirement of that specific employment, then it might be allowed in circumstances when the employer themselves would not pay for it.
In the circumstance you describe, the offer of employment is presumably conditional on obtaining the type rating. It would not therefore be a wholly exclusively and necessary expense incurred in the performance of the employers duties.
As you are not employed by them it is not a legimitate expense, since it would be incurred only in order to put you in a position to obtain employment. They do not care that without the rating you cannot earn the money to pay the tax. They only care that you pay the tax on the monies you actually do earn.
In any event, even in those circumstances where an allowance may be made. It is only done so on the tax paid at the applicants marginal rate. For example if you are required to incur an allowable expense of £5000 say and you are a 22% tax payer. The relief is £1100 not £5000. Tax relief reimburses the tax paid on allowable expenses, it does not reimburse you the actual expense.
It is indeed a cruel world !