Going to lose job through operation!

There are some useful guides at Benefitsandwork guides which might enable you to claim Disability Living Allowance.
However I am not sure from your description of your condition if you would qualify. A visit to a Welfare Rights Organisation would probably be worthwhile anyway, the guide to Getting Help with your Benefits will lead you to alternatives to the CAB if you haven't one locally.

But it may be a marginal claim so putting your case as professionally as possible will make a difference. It will depend on whether for most of the time you need help with personal care or for mobility, if you have difficulty getting about. However for this you do have to be virtually unable to walk and/or need someone with you in unfamiliar places and this doesn't sound like it's your problem.

A successful claim for DLA would improve significantly the amount you get for income support which for a person your age isn't hardly enough to survive.
Benefits for those on a low income
No chance you could get your employer to allow you to work from home? You will if you are unable to "Actively seek work" because of health reasons still have to meet the Personal Capability Assessment criteria which are set out here IB214 A guide to the personal capability assessment
The scoring for which is set out in the calculator here
PCA threshold calculator and again because of the nature of you condition you may find that you need Welfare Rights support as you may be physically capable, as far as the assessing doctor is concerned, of meeting those criteria. (especially on a good day)
I've just been through a spell of one infection after another so am very sympathetic regarding your position however unless your own health professionals are prepared to support your claims you may find it hard to convince the DWP doctors from Medical Services.

But I went back to work for 4 weeks and there's something about an 8-week rule.

What is the 8-week rule for this benefit?

From
A guide to Income Support (IS20 Apr 2004)
If you are claiming Incapacity Benefit based on your National
Insurance contributions, a period of incapacity for work is formed by a period of 4 or more consecutive days. A day of incapacity is a day on which a person is assessed as incapable of work. It includes days when Incapacity Benefit or Maternity Allowance is claimed and paid. It can also include days where benefit is claimed but not paid. Periods of incapacity for work which are separated by not more than 8 weeks link together and count as one period.

Ted,

I'm currently applying for Incapacity Benefit under the Youth rules and am looking at other benefits this can come under.

If you have savings of less than £6000 you should also apply for Income Support, housing benefit and Council tax benefit.

Can I apply for DLA for this back wound even though it is a surgical operation as I phoned up the DLA helpline on Friday and was told I couldn't apply for it for the above reason?

When you apply for DLA you do so not directly on the disease or condition but because of the care needs or walking problems which arise from that condition. Any injury/disease or cause which results in you needing care through the day or night or which means you are Virtually unable to walk outdoors without severe discomfort will do. The requirement is that the "need" must have existed for three months and be expected to last for a further six months. So you need to ask "Has this existed for 3 months and is it reasonable that given the current success of treatments, to consider it will be much the same in six months time. You doctors need to support both the existing need and the likely prognosis for the next sixmonths.
There is more detail of the criteria here Benefitsnow self assessment pages and here benefits and work dla guide and self assessment test
Well worth getting help with your claim and benefits from a Welfare Rights Organisation Getting Help with Your Benefits guide