i did attempt an OU course a while back i ended up dropping it near the end, and resitting the year properly at a college. personally it didn't suit my learning style. but for many others it worked well.
for me it felt very isolated and you are completely reliant on yourself, i felt i lacked support and it can be easy to get lost in all the paper work. but that doesn't mean to say its not a good option.
i've never heard of ICS, but if i was to do an external learning qualification i'd be looking at the OU as their reputation is well regarded and they have been doing it a long time. one thing i've learnt in engineering is that its not just the qualification you hold, but where you got it from that counts.
my degree in engineering is from coventry, a well regarded engineering uni.
the worst thing you want to do is invest alot of hardwork and effort into something that turns out to be worthless when you decide to change profession.
make sure the course is accredited by one of the big institutes like IMECH or IENG etc