protein bars/shakes for UK based person

I have lost a few pounds and now I want to up my workouts. Currently burn anywhere around 200 – 400 a day doing 30mins to an hour of exercise. Now I have got into a routine and am enjoying exercise, I want to increase the intensity and add more weights training. I do a few strength exercises, but need to again increase these.

What I have found over the past few workouts, on which I have increased in length and intensity (I mainly swim) that if I am not eating enough I find it hard to get a good workout and my weight loss is quite low, it is OK, but I would like it to be a bit more. I want to ideally lose 2lbs regularly a week.

I work on eating 1200 – 1400 net on the days I do not work out (which is normally only the weekend) and 1300 – 1500 plus half of workout calories (worked out from an HRM). This has been working fine for the low level of exercise I have been doing.

My % of proteins etc is OK, but I want to have a pre or post workout snack for the days I am going to starting pushing myself more. At this point I must say I still have about 42 – 55lbs to lose and when I say increasing my workouts, it is still only 45 – 60 minutes swimming or 30 – 45 mins light jogging/walking, but this is an increase on what I am currently doing and a major change from what I did a few months ago, which was nothing!

Sorry this is a little long winded, but I do not really want to increase the amount of food. I got myself in to a nice routine of finding 1200 to 1400 is a nice amount of food to eat and do not find myself hungry. So what I do not want to do is increase the volume of food as such as once I get closer to my goal weight I do not want to have to cut back on the amount of food consumption. It has took me a while to get into a routine and an amount where i find it pleasurable to deal with and not too much hard work.

So what I am thinking is a protein bar or shake, I have done various searches and there is quite a lot to take in. Also from some threads not sure whether the posters are UK or another country. I will not miss a shake or bar from my daily intake if I do not exercise or cut down in the future to 3 days a week.

So my question is what products do people use in the UK? I do not really want to bake my own, so need a shake that is easy to mix at work or a bar I can eat in the car etc? Just need something that is full of good stuff to help give me more energy to help work out a bit harder and give me extra calories to help maintain a good 2lb a week.

Hope that makes sense.