Update!
Starting to get a bit fitter I think. It's still seriously hard at times and one particular elevation home is an absolute killer, I still struggle quite badly with it but I'm getting better overall. My work-home time is now down to 34mins on average with one highlight being 31mins, I'm aiming to get that under 30mins but it'll take a while as that 31mins was really pushing it. Keep in mind that when I started, 45 mins felt like an achievement.
My fitness doesn't seem to be improving much but I put that down to my diet as well. Maybe it is. Dunno.
I still get passed by all sorts but it's getting less and less, I'm gradually starting to become the person passing others which is a great feeling.
I'm not in the position to buy a new bike yet having bought loads of things recently (my wife will kill me) but hopefully in a few months I'll pick up something new. Until then I'm stuck with this Raleigh heavyweight monster which suits me fine. Once I'm fit enough to get this thing under 30mins I'll probably do the journey in 30secs on a proper bike
Here's my Strava link in case anyone's interested. All comments and feedback appreciated as always!
http://www.strava.com/athletes/diddums