People use "refit", "renovation" and "refurbishment" fairly interchangeably, but in practice a bathroom refit usually describes one of two quite different jobs, and it's worth knowing which one you need before getting quotes.
A refresh-style refit keeps the existing layout. The suite, tiling and flooring are replaced like for like, pipework stays roughly where it is, and the room gets a new lease of life in around two weeks. It's the most cost-effective route when the layout already suits you and it's just the finishes that have aged.
A full refit or refurbishment strips the room back and reworks it — fixtures move, waste and supply pipework is re-run, walls are prepared or re-boarded, wet areas are tanked, electrics and ventilation are upgraded and everything is retiled. It takes longer, typically three to four weeks, but it's the only way to properly fix a layout that never worked. Taken that far, it's effectively a complete bathroom installation, and we'll quote it as one.