I think a fleshlight would be the perfect tool for you.

Or this:

Buy a barbell for about 40 quid from Argos etc and do Barbell Complex workouts! Miles more efficient than Cardio machines and miles less mind numbing!

It all depends on your budget and preferences. The best exercise is the one you're going to consistently do so even if the optimal approach would be buying a barbell + weights and bench it won't be optimal if you don't enjoy strength training. That being said I'd go with two dumbbells first (Example though you might want to find heavier set so you can put at least 20kg on one dumbbell) and some sort of a bench (Example). It's a relatively cheap solution and it's all you need to start training. If you want to I can even make an exercise program for you based on those dumbbells (recently did that for my younger brother, he started counting calories too and he's 5kg down in three weeks, he also made some quick strength gains).

If weights aren't your thing you can also go for a cardio machine (Example).

The barbell complex routine above is a cardio routine! You choose a moderate weight and perform 4-5 exercises back to back (e.g. 10x squats, 10x bent over row, 10x cleans, 10x overhead press, 10x deadlift)! 60 seconds rest then go again! Do as many of the giant sets as you can! Really easy to progress too by adding weight to the bar/ increase the total number of sets! Great for getting the heart racing, weighted so great for toning/building muscle and great fun so easy to stick to!

I go to the gym 5-6 days per week so just use this as cardio at home! Bought the below plastic barbell from Argos and does the job perfectly:

http://www.argos.co.uk/static/Product/partNumber/1514849.htm

Not a fan of using heavy compound movements and Olympic lifts as a form of cardio. I don't think they were designed for that purpose. Cardio is strenuous enough as it is so I'd much rather either go for 30min of steady state on the elliptical/bike or do a short HITT style workout using kettlebells, bodyweight or short sprints.

As a guy who lost over 35kg in the last few months, I think cardio is actually the least important part of the process. I do steady state semi-regularly after each strength training, but the strength training itself was far more important, with a moderate caloric deficit being absolutely crucial.

Jon clearly does not want a strength training routine or he would just join a gym! That is why my advice was based around a cardio style workout that will give him the most 'bang for his buck'! Well done on your weight loss but I am really not going to get into a 'credentials' type debate! I will leave Jon to take my advice or not as the case may be!

I don't think strength training and training at home are mutually exclusive. Also, there are plenty of reasons someone might want to avoid buying a gym membership (long drive, tight schedule, insecurity), but still be interested in strength training. And yes you're right the 'credentials' argument is unnecessary, there are many people in this world who forgot more about fitness than I'll ever learn, and I'm not going to claim I'm some sort of authority on the subject because I'm not. Again, the most effective exercise is the one you're going to stick with so Jon should make a choice based on his preferences and it's good that we both gave him some options to choose from.