I Follow Roads has it exatly right. The exeperience stated matching exactly with my own. I have had the IR for 3 years (it is actually one of the last of the old CAA ones issued)
Airways flying is extremely simple and easy and a lot safer than VFR.
Departures from places like Wycombe, Fairoaks etc are simple and easy as well. If the tower is active they will normally get your clearance for you, give you a squawk and and a frequency for contacting London. If the tower is closed you merely contact London Inf, give them your airborne time and ask them to activate the flight plan.
Arriving back means you can get dumped from CAS some miles from home but you normally have a radar service available from Thames or Farnbrough in the London area.
Funnily enough the real change for me has been that the weather decision is often much more difficult than when flying VFR. I have even had a case where a VFR departure from Annecy made more sense than an IFR one because of embedded thunderstorm activity above a 6000 ft cloudbase.
Go for it you won't regret it but it will take time and cost you. Once in the IR club a whole world of possibilities opens up.