Some people apply a stigma to HDB's but to be honest I don't see it. As long as the place is clean and the location is where you want it to be then it should be fine.
Many expats cannot see the daylight for the for the trees, they have to be like the majority..its was like that back in the late 60's too, even the soldiers didn't know how to mix, at that time, although one of ours spoke fluent Malay, because his father was a diplomat in Malaya and Katmandu.
I personally would advise you to mix with locals, if you really want to learn about Singapore, like I do myself. In fact that's were the real cultural experience is found.
I really don't understand the isolation of expats, and why they should feel lonely, unless, its their first time away from mummy, true many do have difficulty, to become independant, if they manage it at all.
There is one advantage to sharing. You do get to meet people straight away. It'll stop you from feeling either lonely or even out of your depth. I share and have found it much easier than I initially anticipated. I am used to living on my own but have found that not only do they help you adjust but makes you feel settled in.
That's funny my neighbours who are Chinese, and the rest in the block are segregated from their own races in accordance with HDB policy, but I find them all okay...my neighbours are great...when I moved in I did the rounds, with one of the neighbours to meet everyone!
There are many Brits and Irish living in Singapore, in the local areas, so you would never have a problem, with anything.
In fact, those poki hen huts they build in the UK are the same as the
condos here, so you may feel like home

, I escaped from the prison environment back in the 80's, never to go back, into a cage, thank you very much...I have around 148 sq meter, which suits me just fine, buying it was the right, way to go! Even though it is on a 99 year lease!
So you would never get me in a
condo, for that kind of money....I went to visit a Singaporean in River valley, and I was shocked how small, it was for the money he paid....No thanks HDB are a very good size, and worth every penny...and there are 50 meter swimming pools at the sports centre anyway..
For your allowance, you would have no problem in the HDB area, you can get a 3 bedroom for 1800$, although prices are moving up in the HDB too.
It is a much cheaper way of living than the expatriate way of life, in many ways, if your not on a package, that's how you must live! No hardship for me, quite the opposite, and the extra cash is working!
SMS you should be able to rent at a premium by now, and retire
OP, seems like 24K for London is pretty damn sick too, Although I've heard that the majority are supplemented, with welfare

What a state of affairs that government is in!
Now they have lost so many data discs, even i worry, and i've been away for almost 40 years! You will love it here, with all the blood sweat and tears, working hrs for some!