There is no statutory right to take unpaid leave unless the leave relates to parental or caring obligations, where special laws have been put in place.
So, you do not have a right to take a break to travel - unless you have managed to agree something special with your employer, or your employer operates a contractual scheme allowing unpaid leave.
Many employers do allow longer-serving workers to take extended periods of unpaid leave and return to their old jobs, as a way of keeping valuable staff who might otherwise leave for good.
However, this is governed solely by a company's own policies. Consult your staff handbook to see what the policy is in your workplace.
If you are considering a sabbatical or career break, make sure you take good advice, thinking about issues like continuity of employment, pensions and keeping in touch with your employer. For example, how will your previous years of service be treated if you are made redundant when you return from your career break? Will they count when working out your redundancy pay?
You may be able to agree with your employer that your pre-break service is to be preserved for the purposes of employment continuity while you are away from work, but you must put any agreement in place before you take your break.