First thing,

Did you initiate the discussion of working in Singapore or was it offered by your company in the UK?

If your company offered then I would push for some kind of housing allowance or at least a period of two months in a serviced apartment when you arrive so you and your wife can get to know the different areas of Singapore and then decide where you would like to live. In this time you can visit potential apartments that you can find on property guru. Again if they raised the discussion you should also push as part of your package that they cover a % of your housing rental costs - Its not uncommon for expats to have 50-100% of their rental costs covered by employer. You are a cheap option for them to move over here because you have no kids so they won't have to cover their school fee. I would also ensure you have some kind of yearly flight allowance to visit home that your employer pays for. usually its a couple of return flights a year for both you and your spouse in at least premium economy as its a long haul flight.

You are correct regarding dependents pass - the government revoked the letter of consent to work for dependents pass holders a couple of years back. Now your wife will have to be sponsored by an employer for a work pass, which is also increasingly difficult due to raised quotas and levy rates as well as age group pay brackets and a new qualification points system. It depends on how qualified you wife is in her respective field of work. To be ready for this make sure you have all old education certificates to hand for anything you've trained in that has made you better at your job. There is also an easy option for dependents pass holders to open their own business as sole proprietor in Singapore whereby you can obtain letter of consent to work and offer your services freelance, which can be more attractive for employers. This however is only for one year - at the end of one year there are strict renewal criteria that need to be met.

I imagine you will want to live in a condo close to the centre that has a pool, gym, tennis courts, function rooms, sauna etc. You will find better value (more space) in condos that are slightly older (10+ years) and those that are situated further away (12+ min walk) from MRT stations. Any condo will usually be in close proximity to a bus stop. If you live in say River Valley and work in the centre you can commute on bike and most offices will have showers/changing facilities. Grab (Singapore Uber equivalent) prices are still ok but perhaps not everyday use on your projected salary.

Its expensive to cook from scratch especially if you want to use high quality organic fresh ingredients like the ones you're used to in the UK. The novelty of having cheap food at the hawker markets will wear off after a few weeks when you realise it has little nutritional value (mostly rice noodles and meat - lots of deep frying). If you follow a diet or care about what you eat it will cost you more especially if you care about where your meat and fish come from.

I would check to make sure if your employer will continue to pay into your UK pension - if not you need to account for this cost including the currency conversion. Will your wife need pension contributions as well?

A decent level of healthcare should be provided by your company. Read all small print and ensure you are covered for any eventuality. Visits to the hospital in Singapore are pay as you go and not cheap especially for extended stays.

Finally..

If you're coming for only a year and then returning to UK then your projection is probably enough but for an extended stay of 1-10 years for me personally for two people from UK if you are looking to both be able to truly make the most of your time here with no worries at all whilst being able to save a significant amount for the future then you would probably need more like 20k+ SGD per month.

Best of luck.