Dave70, as Starkesbier said, 10 extra minutes on your mash is nothing to worry about on your first attempt at mashing. You should have a look for some threads relating to brewing mishaps. You had fun doing it and that's the main thing. Being a Bitter it should be ready in no time so let us know what you think of your first effort.
Antcoop, one of the advantages of mashing your own is the control over mash temps and therefore fermentability. As Butters stated though, there are other factors as well. Good extract brewers do get to know their extract and it's fermentability and develop recipes with this in mind. You are lucky to be able to get fresh liquid extract so close to home and this no doubt is a contributing factor to the quality of beer you are producing.
NickJD, you say 'Your friends might even comment that they like your extract beer better - much to your horror'. Are you speaking from experience with this one?
Antcoop, one of the advantages of mashing your own is the control over mash temps and therefore fermentability. As Butters stated though, there are other factors as well. Good extract brewers do get to know their extract and it's fermentability and develop recipes with this in mind. You are lucky to be able to get fresh liquid extract so close to home and this no doubt is a contributing factor to the quality of beer you are producing.
NickJD, you say 'Your friends might even comment that they like your extract beer better - much to your horror'. Are you speaking from experience with this one?
- says the AGs taste more like commercial beers. 
