Back in the mists of time in the MoD Civil Service it was common to have residential courses as well as courses that just involved travel & overnight stays
A ‘normal’ course would typically involve travel & accommodation costs covered, but if local you would just go home - usually the night before plus each night except for the last day of the course
Accommodation where applicable would be booked via the appropriate process
A ‘residential’ course would be intended to involve staying away as part of the course & as additional ‘bonding’ with course mates
These would include it being compulsory to stay even when local
Accommodation would be booked by the course administration
(I’m not aware of any of these in the MoD these days)
For any courses and other business travel you should expect expenses, but will depend on the policy of each department
Expect accommodation and rail travel
to be via a booking service.
Road travel would be either via a department fleet / hires / leases or via your own car with a claimable rate
(This would be claimed at the lowest public mileage rate, and may still have to be justified)
Short(ish) version:
Rail tickets - expect the department to pay directly, probably booked by you via an internal web app
Car provision - expect the department go provide an ‘official vehicle’ booking service, and to provide a card for fuel purchases
Your private car - Expect to need justification, then claim mileage (less a home to duty deduction)
Travel time - You are on duty when making official travel, expect to count your time as part of the working day and / or to claim it as flexi time. You may be eligible for a multiplier for out of working hours time. Eg Saturday was time and a half, Sunday double time and weekdays standard
Other expenses - meals etc are claimable as subsistence, but note that receipts will be required and with maximum caps. Eg on an overnight stay I am entitled to £22.50 for an evening meal. If it costs £15 I can claim £15, if it costs £25 I can only claim £22.50