Out of base travel, subsistence and accommodation can be claimed according to UK rules.  

Expenses can be claimed either as actuals or in line with scale rates published by HMRC.

Subsistence rates for out of base work in the UK have not been reviewed by HMRC since 2009 so are comparatively lower than those in other EU countries.

For out of base subsistence outside of the UK, either actuals or HMRC overseas subsistence rates can be claimed.

Guidance document, procedures for uploading and allowable rates are attached