General principles for UK Visitors
(a) Cannot switch into a visit visa, (exception applies)
(b) All Visa nationals require entry clearance Appendix Visitor: Visa national list
(c) Oman, Qatar, UAE and Kuwait nationals, visa-free visits for up to six months are enabled via the Electronic Visa Waiver (EVW) scheme.
(d) A six-month visit visa costs £95 (different fee payable according to duration requested
(e) Non-visa nationals can travel to the UK and then seek leave to enter as a visitor at the port of entry.
(f) Non-visa nationals seeking to visit for more than six months or visiting for the purposes of marriage of civil partnership, or of giving notice of this.
(g) Non-visa nationals may apply for a visa
As a reminder, work is not permitted unless expressly allowed by Appendix Permitted Activities.