I am not an expert on mobile phones, my knowledge of them is definitely stone age, but the thing for you could be a "Pay As You Go" phone.
Look here:
https://www.carphonewarehouse.com/p...lourCode=BLUE&intcmp=PAYG_Nokia105_99p_180214
A very basic phone cheap as they come, but the individual calls could be expensive. That should not be a problem if work is paying the bill, I guess.
The phone should work anywhere in Europe, but the calls may be a bit more expensive.