My instructors actively encourage me to always be talking to someone on the radio, be that Glasgow Approach when East of Glasgow, Prestwick if staying local or Scottish Info if doing a Navex towards Dunfries. If I'm not talking to someone then I think something is wrong!
From my (very) limited experience I've struggled to contact Scottish below about 2500 feet when South of Prestwick. When I have been able to talk they've been great.