Whilst there doesn’t have to be, there is usually a gap between the exchange of contracts and the completion date. The gap is usually between two and four weeks long. This allows time for both parties (i.e. the buyer and the seller) to organise their personal belongings in readiness for moving. But also to arrange funds from mortgage lenders where appropriate.
The property market is going to be affected by Coronavirus or Covid-19, which means property prices will likely go down and it will stop people from view houses, which in turn will slow the market down significantly.